Except that would probably cause pages to move to the wrong job books... Book 1 page 10 would suddenly become Book 2 page 1, Book 2 page 10 becomes Book 3 page 2, etc... My PUP macros would end up on my WHM macro book...
Not to mention you lose 2 entire pages.

Just have PUP and MNK take 5 pages in 1 book, and WHM and SCH take 5 pages in another, and you got room for 2 more jobs.

I never said it was a perfect solution. But seeing as the devs reason for not adding two new books was merly a 'we dont think its needed' ... i figured a logical argument was out of the question.